Upgraded fan for Series III Heater Blower

I posted this on my continuing thread covering my restoration efforts on my Series III but it is well buried. I thought I’d get better coverage/views with a separate thread. There are similar threads on this topics but mostly covering Series I or XJS, so . . .

This is the original fan motor and mounting flange beside the new fan motor. I don’t remember which thread it was nor how long ago, but I ordered this fan motor based on a Lister using it on his Jag.



The issue is the fan motor is attached to the mounting flange using three equally spaced tabs; the new motor does not have those.

The old motor has a diameter of 76mm while the new one is 75.88mm - I can’t imagine that slight difference mattering.
The original squirrel cage fan fits on the spindle; the new spindle has a flat (while the original does not) but I can align the curve of it with the grub screw


Is it just a matter of swamping the bottom half of the fan motor bodies so the new motor has the mounting tabs? Looks like I may also need to trim the length of the through-bolts or maybe use the original bolts on the Frankenstein motor (the bolts on the original motor look to be custom made while the new one has what looks like all-thread that is too long).

Any help is appreciated


You want the grub screw aligned with the FLAT, not the round part of the shaft.

You can’t mount the new motor the same way the original mounts. The lower portion of the case will be unique to each motor. The long studs on the new motor are intended to bolt to the mounting plate. If the plate can’t accept them as is, then you’ll have to drill holes for them. I would be surprised if the new motor produces more power than the old.

The new motor appears to be dual wound, while the original is controlled by an external resistor. Did they give you wiring instructions? If not, you’ll have some guesswork to figure out how to wire it.

Thanx Mike

and you guessed my next question.
No - the motor is all I received; no wiring instructions.
I did get a new resistor from Barratt so that gives me three: the new one, the used on my heater box and the one on the spare heater box I picked up ears ago.

This is a diagram for an “upgrade” that was floating around about 20 years ago. It may apply to your motor:

No resistor should be required, but you’ll have to fiddle with the wiring.

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Thanx again

I wasn’t clear. Your motor should match the “3 speed”, CCW ground diagram.

Well – that sure saved me a bunch of reading and googling and cross-wiring.
Thanx again, Mike

Hi Craig, why don`t you rebuild your old motor and avoid all the hassles.


Amazing how I can find something from 20 years ago, but can’t find my glasses.

Actually, I think the motor should be set up for clockwise rotation.

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I am moving in that direction.
I have practiced on the two radiator cooling fans . . .

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